CHAPTEE XIV. 



SPHENOPHYLLALES {concluded). 

 Sphenophyllum. 



The account of the Sphenophyllales given in the first 

 volume 2 of this work must be extended and somewhat modified 

 in the light of recent work on the fertile shoots of Spheno- 

 phyllum. 



Sphenophyllostachys Dawsoni (Will.) was described as con- 

 sisting of an axis bearing superposed whorls of bracts connate at 

 the base in the form of a shallow funnel-shaped collar giving 

 off from the upper surface and close to the axis of the cone two 

 concentric series of sporangiophores. Occasionally there are 

 three series, as represented in fig. 112. In another type of 

 strobilus, Sphenophyllostachys Romeri^ each sporangiophore 

 terminates in two pendulous sporangia (fig. 113, A; see also fig. 

 107, C, vol. I.). It has already been pointed out that the common 

 occurrence of detached strobili necessitates their description 

 under distinct specific names ; it is only by a rare accident 

 that we can assign fossil cones to their vegetative shoots. There 

 are, however, reasons for believing that Sphenophyllostachys 

 Dawsoni is the strobilus of the plant originally described by 

 Sternberg* from impressions of foliage-shoots as Rotularia cunei- 

 folia. Another difficulty presented by petrified material is that 

 of determining, with certainty, whether two imperfect specimens, 

 differing from one another in features which do not appear to 



1 The full titles of books and papers referred to in footnotes distinguished 

 by the addition of A after the date are given in the Bibliography at the end of 

 Volume I. 



2 Chap. XI. 3 ihid. p. 405. 



« Sternberg (23) A. p. 33, PI. xxvi. figs. 4 a, 4 6. 



